1. Field of the Invention
The present invention relates to film developing systems, and more particularly relates to an automatic microfiche duplicator using for example vesicular film or other heat developed film processes or diazo process.
2. General Background and Prior Art
Microfiche photographic duplicating techniques are well known; several processes are employed. At least one process, vesicular photography, is a duplicating method using light and heat alone, without chemical processing. It is to the field of vesicular photography that the preferred embodiment of the present invention is primarily directed.
Briefly, vesicular photography may be explained as follows:
Vesicular film has a thin layer of photosensitive emulsion coated onto a suitable support, either transparent or opaque. The main ingredient is a themoplastic resin which, under normal storage and use conditions, is hard and stable. Within this resin layer, which is normally between 0.0002 inches and 0.0005 inches in thickness, there is uniformly dispersed an ultraviolet sensitive compound, or sensitizer, chemically similar to the compounds employed is diazotype papers and films. Upon exposure to ultraviolet light, the sensitizer decomposes, and one of the products of its photolysis is nitrogen gas, which is trapped within the plastic layer and constitutes a "latent image." This latent image is converted to a visible image by the application of heat. The thermoplastic softens and the gas expands to form microscopic bubbles or "vesicles". These vesicles are the image elements of the vesicular film. In contrast to the conventional silver-halide photography and diazotypy, the vesicular process yields a light-scattering image rather than a light absorbing one.
While duplicating devices which employ the vesicular process have been constructed, none have provided a fully automatic, single copy or single shot duplicator. Typically it has been necessary for the operator of such devices, which have been very complex and expensive, to continuously handle and be with the film for up to one minute to get a copy. Changing master sheets is usually a cumbersome procedure. Some duplicators use only roll film and require accurately keyed cutting mechanisms, which further add to the complexity and expense of those devices.
The present invention eliminates this problem by providing in its preferred embodiment a fully automatic heat development type film duplicator which yields copies in little more than ten seconds. It achieves this time efficiency in a most compact, simple, reliable and relatively inexpensive device.